Minimally invasive medical procedures allow diagnostic tests and corrective surgeries with a minimal amount of damage to healthy tissues. For example, laparoscopic surgery, which is minimally invasive surgery on the abdomen, generally introduces surgical instruments through small incisions. The inserted instruments are typically rigid, have small diameters, and end with effectors that can be manually or robotically controlled to perform a desired medical procedure on a work site. Laparoscopic surgery typically uses two or more incisions to provide separation between the instruments and to allow insertion of the instruments from different directions for triangulation on the work site inside the body. The separation and triangulation of instruments is often critical to allowing the instruments to work cooperatively during surgical manipulations.
Endoscopes are also known that are sufficiently flexible to be inserted via a natural orifice and to follow a natural lumen such as the digestive tract to a work site. Medical instruments can then be inserted through such an endoscope to reach the work site. In particular, a multi-channel endoscope can act as a flexible conduit for simultaneous insertion of multiple diagnostic or surgical instruments, but the flexibility of these endoscopes have limited the controllable degrees of freedom of the instruments at the work site. For example, a flexible endoscopic system may only provide control of roll, insertion/extraction, and sometimes grip. Further, the instruments inserted through an endoscope must be sufficiently flexible to follow channels provided in the endoscope and typically run parallel to the centerline of the endoscope. As a result, flexible endoscopic instruments generally have minimal separation from one another and little or no triangulation relative to each other. This makes basic surgical manipulations such as suturing difficult, if not impossible to accomplish with conventional flexible endoscopic equipment.
Medical systems have been proposed that attempt to provide separation and triangulation of instruments delivered through a flexible endoscope. U.S. Pat. No. 7,029,435 to Nakao, for example, describes an endoscope having a distal end that is longitudinally split into segments that can be made to separate after the endoscope reaches a work site. U.S. Pat. No. 6,761,685 to Adams et al. and U.S. Pat. No. 6,352,503 to Matsui et al. describe endoscopes having instrument lumens at the perimeter of the endoscope cross-section so that the separation of inserted instruments is about equal to the diameter of the endoscope, and further separation or triangulation of the instruments can be achieved by deflecting the instruments or the lumens that guide the instruments. However, most current approaches to providing separation and triangulation of instruments in a flexible endoscope require a relatively long length to create a relatively small separation, and the instruments generally lack solid support and have little or no useful triangulation.
In view of the current state of minimally invasive medical equipment and procedures, it would be desirable to have simple devices and procedures for achieving useful triangulation and working separation between instruments at the distal end of a rigid or flexible endoscope. Ideally, the device would be such that device failures occur only in a safe manner that permits withdrawal of the device.